feat(xtream-proxy): rewrite proxy logic and update configuration format

Refactor the xtream-proxy from a single-file Express-based server to a
modular Node.js application using native http/https modules. This
change introduces a major version bump to 2.0.0.

- Replace `hosts.txt` with `upstreams.json` for configuration
- Remove heavy dependencies (`express`, `ws`) in favor of native modules
- Implement new environment variables for proxy credentials and timeouts
- Add `src/` directory for modular code structure
- Add `docker-compose.example.yml` for easier deployment
- Update Dockerfile to support the new directory structure and environment
- Improve error handling and probe logic for upstream selection

Dockers/xtream-proxy/upstreams.json.example

@@ -0,0 +1,19 @@
+#
+# Every entry must point to an Xtream-compatible panel that serves the same
+# content. The proxy probes each entry via /player_api.php and picks the
+# fastest one that is not at its connection limit.
+#
+# The URL may include a path prefix, e.g. https://example.com/portal
+#
+[
+  {
+    "url": "http://panel1.example.com:8080",
+    "username": "user1",
+    "password": "pass1"
+  },
+  {
+    "url": "https://panel2.example.com",
+    "username": "user2",
+    "password": "pass2"
+  }
+]